Lexus RX300 (MCU15). Service manual - part 215

DI–92

–

DIAGNOSTICS

ENGINE

LEXUS RX300   (RM785E)

5

Check air induction system (See page FI–1).

NG

Repair or replace.

OK

6

Check fuel pressure (See page FI–5).

NG

Check and repair fuel pump, pressure regulator,
fuel pipe line and filter (See page FI–5).

OK

7

Check injector injection (See page FI–22).

NG

Replace injector.

OK

Replace A/F sensor.

8

Perform confirmation driving pattern (See page DI–85).

Go

9

Is there DTC P1133 or P1153 being output again?

YES

Check and replace engine ECU 
(See page IN–32).

NO

–

DIAGNOSTICS

ENGINE

DI–93

LEXUS RX300   (RM785E)

10

Did vehicle runs out of fuel in past?

NO

Check for intermittent problems 
(See page DI–3).

YES

DTC P1133 or P1153 is caused by running out
of fuel.

A02032

HAFL

ON

HAFR

(+)

(–)

DI–94

–

DIAGNOSTICS

ENGINE

LEXUS RX300   (RM785E)

DTC

P1135

A/F Sensor Heater Circuit Malfunction (Bank
1 Sensor 1)

DTC

P1155

A/F Sensor Heater Circuit Malfunction (Bank
2 Sensor 1)

CIRCUIT DESCRIPTION

Refer to DTC P0125 on page DI–42.

DTC No.

DTC Detecting Condition

Trouble Area

P1135

When the heater operates, heater current exceeds 8 A

S Open or short in heater circuit of A/F sensor

A/F

h

t

P1135

P1155

Heater current of 0.25 A or less when the heater operates

S A/F sensor heater

S Engine ECU

WIRING DIAGRAM

Refer to DTC P0125 on page DI–42.

INSPECTION PROCEDURE

HINT:
Read freeze frame data using hand–held tester or OBD scan tool. Because freeze frame records the engine
conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the
vehicle was running or stopped, the engine was warmed up or not, the air–fuel ratio was lean or rich, etc.
at the time of the malfunction.

1

Check voltage between terminals HAFL, HAFR of engine ECU connector and
body ground.

PREPARATION:
(a)

Remove the glove compartment (See page FI–70).

(b)

Turn the ignition switch ON.

CHECK:
Measure the voltage between terminals HAFL, HAFR of the en-
gine ECU connector and body ground.
OK:

Voltage: 9 – 14 V

OK

Check and replace engine ECU (See page
IN–32).

NG

DI2H9–06

–

DIAGNOSTICS

ENGINE

DI–95

LEXUS RX300   (RM785E)

2

Check resistance of A/F sensor heater (See page FI–56).

NG

Replace A/F sensor.

OK

3

Check A/F sensor heater relay (Marking: A/F) (See page FI–56).

NG

Replace A/F sensor heater relay.

OK

Check and repair harness or connector between A/F sensor heater relay and A/F sensor, and A/F
sensor and engine ECU (See page IN–32).